System for removing a defect in a tooth and insert or tool for such a system

ABSTRACT

System for the removal of a defect in a tooth ( 71 ), consisting of an oscillatingly movable tool ( 3 ) having working surfaces ( 56 ) for an abrasive making of a cavity (K) in the tooth, a filling material for filing the cavity (K), an insert ( 91, 91 A) which can be placed into the cavity (K), which with regard to its surface region surrounded by the cross-sectional walls (KW) of the cavity (K) is pre-fabricated adapted to the dimension and shape, and a binding material ( 92 ), which hardens or cures, for bonding the insert ( 91, 91 A) with the walls (KW) of the cavity (K).

CROSS REFERENCE TO RELATED APPLICATIONS

This is a division of application Ser. No. 08/669,344 filed Jul. 2,1996, now U.S. Pat. No. 6,022,217.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a system or a tool or an insert for the removalof a defect in a tooth or for making a cavity in a tooth.

There are various causes which justify the making, by machininginvolving the removal of material, of a cavity in a tooth and the repairof the tooth by means of a treatment of the cavity. Such a measure maybe effected e.g. for aesthetic reasons to remove an unsatisfactory formof a part of the tooth. In most cases, however, these measures arecarried out for repairing an unhealthy tooth, namely for removing acarious defect. A further reason for a measure as described above canalso be the exchange of tooth fillings which are unsatisfactory for avariety of reason.

2. Description of the Related Art

In DE 42 09 191 A1 there are described a device and a process for thetreatment of natural hard tissue with the employment of oscillatingtools. With this known device, to make an occlusal cavity, a tool isused which has at its surface geometrically defined cutting edges or hascutting edges of non-defined geometric form such as adherent diamondgrains, which make possible working of the material of the tooth, withthe removal of material, with the oscillating movement of the tool. Withthe tool, there is made a cavity having an inwardly convergingperipheral wall the cross-sectional size of which is a multiple of thecross-sectional size of the tool and the cross-sectional form of whichdiffers substantially from the cross-sectional form of the tool. Thetool is held releasably in a handpiece by means of a mounting device.The tool has a fluid outlet, at a spacing to the rear from the handpiecehead which receives the tool, through which outlet a flow of fluid, e.g.water or a saline solution, can be directed at the treatment site andonto the tool for the purpose of cooling and rinsing. Measures forfilling the cavity and treating the tooth are not described in thisdocument. This known device and this known process are not only work andtime consuming so far as the preparation of the cavity is concerned butalso with regard to the usual methods of filling the cavity, whereby inthis respect demands are made on the practicability of the preparationwork and treatment work, on the thereby necessary manipulability, on thefirmness and load bearing and on the lifetime of the treatment.

The above described treatment measures in a tooth occur not only in itsocclusal region but also in its lateral and approximal region. Inparticular approximal preparations and treatments are difficult to carryout because of a neighbouring tooth and the thus resulting restrictedaccessibility, whereby there is a danger of damage to the neighbouringtooth.

The treatment of a cavity with a laboratory-prepared inlay iswork-intensive and correspondingly expensive. Further, the tooth to betreated can be definitively treated only in a second treatment sessionand thus with “double time”. To reduce the outlay involved in atreatment, it has already been proposed to use inlays manufactured atthe place of treatment, as is e.g. possible with the so-called computercontrolled milling of inlays. Further, it has already been proposed touse for the treatment of cavities prefabricated inlays, whereby likewisea treatment in only one treatment session and thus at a “single time” ispossible. With such a measure, however, special preparation andtreatment measures are needed which are again time consuming and involvecomplicated manipulation and are expensive.

The object of the invention is to improve a system, an insert or a toolfor removing a defect in a tooth.

According to one aspect of the invention, there is provided a materialremoving tool for working on a tooth to make a tooth cavity byoscillating movement, such tool comprising a shaft and an abrasivetreatment section and characterized in that the abrasive section isformed by a working head having an abrasive working surface and anopposing smooth surface.

According to another aspect of the invention, there is provided novelinsert for filling a cavity on a tooth which has been worked using anoscillatingly moveable tool, wherein the body of the insert ispre-fabricated so that its surface area enclosed by the cross-sectionalwalls of the cavity of its entire cross-sectional area is adapted to thecross-sectional dimension and shape of the tool and comprises bearingsurfaces for abutting diverging edge surfaces on the cavity.

With the system in accordance with the invention there are employed atool working in an oscillating manner for the preparation of a cavity,and an insert which can be inserted into the cavity, which are matchedone to the other at least in the region which is defined by the toothwall of the cavity surrounding the insert. By these means it is possibleto prepare an exactly matched cavity and to treat the tooth withoutneeding to direct special attention the matching form of the cavity andthe insert. This is provided in that a tool working in an oscillatingmanner is used which, because of the oscillation, is independent of arotational movement and thus can be manufactured in selected forms. Withall these forms there can be produced in the tooth, in a simple manner,by machining involving the removal of material, a cavity correspondingto the form of the tool. The tool need only be sunk, oscillating, intothe tooth material. Thereby a particular form for the cavity isautomatically achieved. Thus, in that in accordance with the inventionan insert is employed which is matched to the form and size of the toolat least in the region formed by the walls of the cavity, no specialmeasures are needed for matching the form of the cavity to the insert,since agreement is reached automatically. The term agreement is to beunderstood in the sense that the form and size of the insert, takinginto account a small amount of play or a small gap, correspond to therelated form and size of the tool or of the cavity. Such an amount ofplay can be provided as a small difference in size or this amount ofplay can be provided automatically because of the oscillating movementof the tool. Such an amount of play is necessary in order to be able toplace the insert into the cavity without jamming. Thereby, it is to betaken into the consideration that because of the roughness of the wallsurfaces of the cavity a certain amount of play is of advantage.Further, the amount of play or the gap is needed to be able to placetherein plastic and curing or hardening bonding material and to ensureon the one hand a firm and on the other hand a sealed bond between thetooth and the insert.

The invention thus makes possible a simple, readily manipulabletreatment of a tooth that can be rapidly carried out, which is not onlyeconomical but also of particular quality with regard to its firmnessand load bearing and lifetime.

The system in accordance with the invention is suitable particularlyadvantageously for a treatment in the inaccessible approximal region ofthe teeth. Thereby, damage to the neighbouring teeth can be avoidedsince those surfaces of the tool which in the course of preparation comeinto contact with the neighbouring tooth surface are not configured forremoving material.

The surfaces of the tool and the associated insert which do not belongto the region which is defined by means of the wall surfaces of thecavity need not to be adapted one to the other in the above-describedsense. When such a region surface is a lateral or approximal surface ofthe insert this can likewise be pre-fabricated e.g. in an idealizedform. In the occlusal region of a purely occlusal or also lateral orapproximal cavity, the insert may be larger than is necessary and afterattachment in the cavity may be adapted through machining involvingremoval of material. This is naturally true also for a lateral surfaceof the insert. Within the scope of the invention it is however alsopossible to provide the vertical dimension for an occlusally open cavitysmaller than the necessary dimension and after attachment of the insertin the cavity to complete this dimension by means of a building up ofmaterial, e.g. at the same time as a region extending to a neighbouringor to the other occlusal region of the tooth.

It is advantageous to provide at a treatment station a plurality oftools and a plurality of mold parts adapted thereto in the sense inaccordance with the invention, which with regard to their size in oneand/or both dimensions, their cross-sectional form and/or their heightand/or their coloring are different. By these means it is not onlypossible to use for a particular size of the defect a correspondinglydimensioned tool and also an associated insert, but it is also possibleto make a cavity through the use one after another of progressivelylarger tools in a plurality of working steps.

A further advantage of the invention consists in forming mutuallyoppositely lying surfaces of the tool convergingly in the forwarddriving direction of the tool so that the tool worked into the toothmaterial can be withdrawn from the thus formed cavity without jamming.

Further, the invention relates also to a tool and an insert having thefeatures in accordance with the invention. The above describedadvantages apply also to the tool and the insert part.

The invention relates also to a process for removal of a defect in atooth which is advantageous for the same or corresponding reasons.

BRIEF DESCRIPTION OF THE DRAWINGS

Below, the invention and further advantages which can be achievedthereby will be described in more detail with reference to advantageousembodiments and to the drawings, which show:

FIG. 1 a tool in accordance with the invention, in a side view, with anassociated handpiece for the attachment and manipulation of the tool, inaxial section;

FIG. 1a working head of the tool in a view from above;

FIG. 1b the working head in a perspective representation;

FIG. 1c a working head of the tool in a side view;

FIG. 2 the tool in a modified configuration;

FIG. 2a a tool in accordance with FIG. 2 in a further modifiedconfiguration;

FIG. 3 the section III—III in FIG. 2;

FIG. 4 a tool in a further modified configuration;

FIG. 4a the tool according to FIG. 4 in a further modifiedconfiguration;

FIG. 5 the section V—V in FIG. 4;

FIG. 6 tool in a further modified configuration;

FIG. 6a the tool according to FIG. 6 in a further modifiedconfiguration;

FIG. 7 the section VII—VII in FIG. 6;

FIG. 8 the tool according to FIG. 6 in a side view from the left;

FIG. 9 a tool in a further modified configuration;

FIG. 9a the tool according to FIG. 9 in a further modifiedconfiguration;

FIG. 10 the section X—X in FIG. 9;

FIG. 11 the tool according to FIG. 9 in a side view from the left;

FIG. 12 a tooth, in a view from above, with a plurality of schematicallyindicated working heads of different sizes;

FIG. 13 the arrangement according to FIG. 12 in a side view from theleft;

FIG. 14 a tool with a handpiece in a modified configuration;

FIG. 14a the tool according to FIG. 14 in a modified configuration;

FIG. 15 the section XV—XV in FIG. 14;

FIG. 16 a tooth, in a view from above, with a pre-prepared cavity;

FIG. 17 the tooth according to FIG. 16 with a measuring tool formeasurement of the cavity;

FIG. 18 the arrangement according to FIG. 17 in a side view, partlysectioned;

FIG. 19 the tooth, in a view from above, with a working head arranged inthe cavity;

FIG. 20 the arrangement according to FIG. 19 in a modifiedconfiguration, in a side view, partially sectioned;

FIG. 21 the tooth, in a view from above, with an insert placed in thecavity;

FIG. 22 the arrangement according to FIG. 21 in a side view, partiallysectioned;

FIG. 23 a press or mold form for a plurality of inserts, in aperspective representation;

FIG. 24 an insert, in perspective representation, in a modifiedconfiguration;

FIG. 25 a press or mold form for an insert in accordance with FIG. 24,in a perspective representation;

FIG. 26 a tooth with an approximal insert and an occlusal insert,partially sectioned;

FIG. 27 a tooth and a cavity with a tool placed therein, in modifiedconfigurations, in a side view, partially sectioned;

FIG. 28 a tooth and a cavity with a tool placed therein, in furthermodified configurations, partially sectioned;

FIG. 28a the tooth according to FIG. 28 in the treated condition;

FIG. 29 a tool in a further modified configuration, in a side view;

FIG. 30 the partial section XXX—XXX of FIG. 29;

FIG. 31 the partial section XXXI—XXXI of FIG. 29;

FIG. 32 a longitudinal section through a tool in a further modifiedconfiguration;

FIG. 33 a working head according to FIG. 32, in a side view from theright;

FIG. 34 the section XXXIV—XXXIV in FIG. 33;

FIG. 35 a working head in a further modified configuration in a viewfrom the front to an enlarged scale;

FIG. 36 the working head according to FIG. 36 in a side view;

FIG. 37 a working head in a view from the front, in a further modifiedconfiguration;

FIG. 38 the working head according to FIG. 37 in lateral section;

FIG. 39 the working head in a view from below;

FIG. 40 a tooth with a working head according to FIG. 37, in a view fromabove.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The handpiece consists of an elongate round grip sleeve 1 in which thereis arranged an oscillation generator 2—which is preferably releasablyconnected with the tool 3—for bringing the tool 3—mounted at the forwardend of the grip sleeve 1 so that it is able to oscillate—intooscillation and thereby to transmit oscillation to the tool 3. The gripsleeve 1 has, in its interior, two treatment medium lines 4 which extendfrom the rear forwardly. Via connection lines 7 of a connection piece 5arranged at the end of the grip sleeve 1 away from the tool, thesemedium lines 4 are connected to respective connection lines 6 leading toa medium source which is not illustrated, which connection lines extendin a flexible supply hose with which the connection piece 5 isconnected.

The connection piece 5 is formed as a quick-release and quick-assemblyrapid-action coupling which is freely rotatable relative to the gripsleeve 1. The rapid-action coupling and the end of the grip sleeve 1away from the tool are provided with medium transfer means 8, 9 whichare functional in any rotational position, whereby cooling medium exitopening of one of the connection lines 6 and 9 is a cooling mediumsupply channel of a cooling medium line 25 leading to the tool 3.

As a further medium line 4, there is provided an energy supply lineextending to the oscillation generator 2.

As an additional medium line 4 there is provided the cooling medium line25 leading to the tooth de-scaling tool 3. The cooling medium may beair, water or a spray formed by means of an air-water mixture. Thecooling medium line 25 opens into the tool 3 which is formed to behollow, which has a cooling medium exit opening directed at thetreatment zone or exit openings emerging at its working surfaces. Thehollow channel of the tool 3 is indicated with 27.

The connection piece 5 is provided with a central guide pin 28, circularin cross-section, which can be inserted and latched into the end of thegrip sleeve 1 away from the tool, relative to which guide pin the gripsleeve 1 is freely rotatable also in the latched-in condition.

In detail, the medium transfer means are formed each by exit openings 8of the connection channels 7 connected to the connection lines 6, whichexit openings surround the guide pin 28 and come into contact on thegrip sleeve inner walls and are arranged on annular sealing elements 29,and are also formed by the ring channels provided in the region of thegrip sleeve inner wall and associated with the exit openings 8.

The connection piece 5 has at least one control member 31, provided witha setting member 30 which is externally actuable, associated with atleast the medium line 4 provided as cooling medium line 25.

Insofar as the elasticity of the sealing elements 29 is not sufficientto provided a clamping force which can bring about a latched-inretention of the guide pin 28 in the grip sleeve 1, there can beprovided for this purpose, as represented, a special latch arrangement39 which retains the guide pin 28 in the desired axial insertedposition. For this purpose, there is arranged on the outer wall of theguide pin 28 a special latch ring channel 35 and there is arranged inthe wall of the grip sleeve 1 at least one latch ball 37 mounted in arecess 36. The latch ball 37 thereby engages into the latch ring channel35, under the effect of a spring 38, with the smaller part of itssurface projecting beyond the inner surface of the wall of the gripsleeve 1. For this purpose, the recess 36 has a floor aligned with theabove-mentioned inner surface of the wall of the grip sleeve 1, whichfloor has an opening which is smaller than the equatorial plane of thelatch ball 37. During the insertion procedure or during the pullingapart procedure, the latch ball 37 is moved out of the latch ringchannel 35 against the effect of the spring 38 so that upon theinsertion procedure or the pulling apart procedure an easy and quicktaking up and release of the latch-in position is provided.

The tool 3 consists of a shaft 41, a working head 42 at the forward endof the shaft 41 and a connection element 43 at the rearward end of theelongate shaft 41. With the present screw connection there is provided athreaded pin 44 which projects backwardly from a rotation engagementelement 45, here a collar in the form of a hexagon. The rearward end ofthe rotation engagement element 45 is formed conically. With this outerconical surface 46, the tool 3, in the connected condition, abuts on acorrespondingly formed internal conical surface 47 at the tool-side endof a bearing sleeve 48 which is connected in one piece or in two pieceswith the sleeve-like resonating body 15 and is mounted in a bearing ring49—which also forms the mounting 17—without play or with slight play formovement, which bearing ring 49 is attached to the grip sleeve 1 in theforward end region of the sleeve and may be formed by means of a ring ofelastic material which sits in an internal groove 51 in the grip sleeve1, whereby the bearing sleeve 48 penetrates the associated through-hole52 in the grip sleeve 1 with radial spacing. In the mounting sleeve 48there is arranged a coaxial bore having an internal thread 53, intowhich the threaded pin 44 can be screwed.

The shaft may extend straight or obliquely to the longitudinal middleaxis of the preferably straight grip sleeve 1. In the presentconfiguration, the shaft is a round rod the cross-sectional size ofwhich continuously tapers down to the working head 42. Starting from thefoot region of the shaft, the shaft 41 extends first obliquely to oneside of the handpiece 1, and it is then bent towards the other side,whereby this shaft section 41 a, extending in the oblique positionpreferably straight, extends beyond the longitudinal middle axis 54 sothat the working head 42 is located at a spacing a from the longitudinalmiddle axis 54 in an oblique position on the other side. In the presentconfiguration, the spacing a is about 5 mm.

The shaft may be formed by a tube which is placed in a correspondinghole in the rotational engagement element 45 and is connected therewith.The hollow channel 27 extending in the shaft 41 or the tube can open outin the region of the shaft in a position directed towards the workinghead 42. Preferably, the hollow channel 27 extends longitudinallythrough the shaft 41 up into the working head 42, as will be describedbelow. The shaft 41 is preferably of high tensile springy material,preferably alloyed steel.

As can be understood from FIGS. 1a, 1 b and 1 c the working head 42 is ablock-like body having a rear wall 56 a, a forward wall 56 b oppositethereto, and two mutually oppositely lying side walls 56 c, a floor wall56 d and an upper wall 56 e in the region of which, preferably in themiddle, the working head 42 is nonreleasably connected with the shaft 41preferably by means of soldering or welding. The cross-sectional size ofthe working head 42 tapers, preferably continuously, from the topdownwardly. The circumferential walls, which are flat in the presentexemplary embodiment, thereby enclose an angle with the associatedvertical of about 2 to 8°, in particular about 4 to 6°, so that themutually oppositely lying walls converge downwardly. The vertical edges57 and the circumferential edges 58 of the floor wall 56 c arepreferably rounded.

For the use of the working head 42 in the middle occlusal region of atooth, all wall surfaces 56 a to 56 d of the working head 42 areprovided with a plurality of in particular point-like cutting edgeswhich are arranged distributed over the associated surface and withoscillating drive provide for the preparation of a cavity in the tooth.Here, the cutting edges may be geometrically defined or undefined.Preferably, the working surfaces 56 are occupied by hard adherent grainspreferably of diamond feldspar or ceramics, and are thus abrasive. Theremay also be other abrasive working surfaces 56 which upon oscillatingmovement provide a removal of the tooth material.

With a working head 42 set up in particular for the approximal region,the surface F towards the neighbouring tooth is formed to be smooth sothat it cannot damage the neighbouring tooth and can form a free orsupport surface F for support on the neighbouring tooth.

Thereby, the smooth surface F may be one of the four lateral workingsurfaces 56. Preferably, the rear wall 56 a or the front wall 56 b formsthe smooth support surface F. This is determined for reasons ofmanipulation and the geometrical position of the approximal toothsurface to be treated (directed to the rear or to the fore) in the mouthof the patient. For the same reason it is advantageous to arrange toworking head 42 so turned or rotated that the rear surface 56 a or thefront surface 56 b encloses an acute angle w of approximately 60 to 80°,in particular approximately 70 to 75°, with the associated verticallongitudinal plane E.

With the configuration of the working head 42 in accordance of FIG. 2,in which the same or similar parts are designated with the samereference signs, the working head 42 a is, with regard to its dimensionb transverse to the shaft 41 and extending in the longitudinal directionof its middle axis 54 a, preferably smaller than its dimension ctransverse to the shaft 42 and transverse to the middle axis 54 a, sothat it has approximately the form of small plate or tip. With thisconfiguration, the rear surface 56 a of this working head 42 a is formedto be smooth whereby it can be flat or also—seen along the shaft42—rounded in the shape of a section of a cylinder. This configurationis particularly well suited for an approximal preparation, which isalready provided in that the dimension b is relatively small and in thepresent configuration is only about 1 to 2 mm, whilst the dimension cmay be about 1.5 to 5 mm and the dimension d transverse to the middleaxis 54 a and extending longitudinally of the shaft 41 is about 3 to 6mm. The working in or advancing direction 40 is approximately parallelto the axis of the tooth starting from its occlusal surface.

Preferably, with an exception at the upper wall 56 e, in the edge regionall three remaining peripheral edges of the rear surface 56 a arearranged as divergent surfaces 59, in particular oblique surfaces orchamfers, on the side walls 56 c and the floor wall 56 d which can runout into the peripheral edges of the front surface 56 b and as with theother working surfaces 56 are occupied by material removing cuttingedges as particles. Thereby, the transitions between the rear wall 56 aand the side walls 56 c or the floor wall 56 d, or between these, andthe divergent surfaces 59, can be rounded. The front wall 56 b can, withreference to the middle axis 54 a, be parallel or somewhat downwardlyconvergently inclined. These divergent surfaces 59 generate in theassociated peripheral region of the cavity K corresponding edge surfacesKW1 at the edge of the cavity walls KW. The angles w1 of the divergentsurfaces 59 may be about 30 to 60° in particular about 45°.

There may be arranged divergent surfaces, comparable with the divergentsurfaces 59, also in the region of the peripheral edges of the upperwall 56 e on the working head 42, whereby in this occlusal region allfour walls 56 a, 56 b, 56 c are provided with corresponding divergentsurfaces.

With the configuration according to FIGS. 4 and 5, in which the same orsimilar parts are likewise given the same reference signs, the workinghead 42 b is provided with a convexly rounded forward and rearwardworking surface 56 f, whereby this surfaces can be formed as section ofa sphere or hemispherically. The front surface 56 a, facing theneighbouring tooth, is on the other hand formed as a smooth free surfaceF. Such a configuration serves preferably for preparation of a smallcavity K in particular in the approximal region of the tooth. In thetransition region between the working head 42 b and the shaft 41 theremay be provided a tapered neck-shaped shaft transition having a forwardworking surface 56 g which is arched convexly towards the rear side,e.g. in the form of a section of a cylinder, in particularhalf-cylindrically or half-conically. Such a working head 42 b hasapproximately the form of a half pear.

With the working heads provided for an approximal preparation the smoothsurface F, facing the neighbouring tooth, may be—seen longitudinally ofand/or transversely of the shaft 41—lightly concavely rounded in thesense of a chamfer, whereby this concave rounding is adapted to theneighbouring tooth and is rounded corresponding to an average value.

Within the scope of the invention it is also possible to configure theworking head flat such that it in substance has only divergent surfaces59 and thus serves for the application of divergent edge surfaces KW1 toa cavity K which is already present. With smaller dimensioning of thisform, the preparation of the smallest chamfer-like cavities is alsopossible, in particular in the space between teeth on the firsttreatment of carious defects. Such configurations are described in FIGS.6 to 11. With the configuration according to FIGS. 6 to 8 there isprovided a working head 42 c in the form of a flat strip with parallelsides which at its free end may have a flat or rounded end face. Theworking surface 56 a, which is at the rear side in the presentconfiguration, is rounded in the shape of a section of a cylinderwhereby this rounding transforms into a rounded or oblique end face at56 i. With this configuration, the working surfaces 56 h, 56 i form thedivergent surfaces 59 whereby these divergent surfaces 59 may also beformed by means of oblique surfaces of striplike head 42 c. When thefree surface F is concavely rounded in the sense of a chamfer, see FIG.7, then this chamfer ends before the free end of the working head 42 c(see FIG. 8), so that the end face working surface 56 i can be formed.

The configuration of the working head 42 d in accordance with FIGS. 9 to11 differs from that according to FIGS. 6 to 8 in that the form of thestrip is not parallel but is formed with an egg shape as is shown byFIG. 11. Since this working head 42 d is longitudinally rounded there isprovided an ellipse-shape convex working surface 56 k. As FIG. 9 showsby way of example it is also possible with all above-described exemplaryembodiments to round the free surface F—seen in longitudinal and/ortransverse direction—lightly concavely in accordance with an averageamount.

The working surfaces 56 f to 56 k are abrasive through the presence ofmaterial-removing cutting edges or particles, e.g. are diamondised; havediamond applied thereto. The working surface 56 k may also be formed asa smooth free surface. The edges may be rounded and not abrasive.

With the configurations according to FIG. 6 to 11, the dimension c maybe so large that cavities K of different widths may be worked with oneand the same working head 42 c, 42 d, whereby the diverging edgesurfaces KW1 at the sides and at the floor of the cavity A can be workedin simultaneously. When the dimension c is smaller then the associatedwidths of the cavity K, then there is needed a lateral movement of theworking head 42 c, 42 d in order to be able to work in the divergentedge surfaces KW1 one after another.

In all above-described configurations in accordance with FIGS. 2 to 11,the working surface 56 and the free surfaces F may face respectively inopposite directions, as is shown by FIGS. 1c, 2 a, 4 a and 6 a. Thearrangement in each case is dependent upon whether an approximal cavityK is to be prepared in the rearwardly facing or forwardly facing side ofa tooth.

The working surfaces 56 to 56 k are of corrosion resistant material,such as e.g. alloyed steel, whereby the working surfaces are providedwith a diamond coating and are thus have diamondised.

With all above-described exemplary embodiments it is advantageous toprovide in each case a plurality of working heads of one basic form, ofwhich the dimensions b and/or c and/or d differ in accordance withparticular steps. Such a configuration is made more clear by FIGS. 12and 13 which schematically show respective working heads 42 to 42 d infive or more differing sizes. With a working head intended for anapproximal preparation, with greater dimension c the divergence of theside surfaces 56 c—approximately parallel to the occlusionsurface—increases, so that the side surfaces—in the case of box typecavities—include an angle w2 of approximately 70 to 90° with a toothtangent T.

Further, it is advantageous to provide for each particular size not onlya single working head but a plurality, in particular two working heads42 to 42 d, of which one working head is intended for a roughpre-preparation and the other working head is intended for a fine orfinal preparation. In the case of a diamondisation, for a prepreparationthis may be approximately 60 to approximately 80 μm, and for a finepreparation approximately 25 to 40 μm. The dimensioning of thepre-preparation instrument should be, with diamondisation applied,slightly smaller—in dependence upon the material removal properties—thanthe fine preparation instrument. Through the cavity provided by thepre-preparation, a defined sinking in of the fine preparationinstrument, a fine removal of tooth material and a reproducible form andsize of cavity is possible.

With the configuration according to FIGS. 14 to 15, in which the sameand similar parts are likewise provided with the same reference signs,there is associated with the tool 3 or working head 42 a—provided for anapproximal preparation—a protection part 56 which is located on the sideof the working head away from the working region, namely on the sidedirected towards the neighbouring tooth. With the present configuration,the protection part 65 is a narrow strip the width which is preferablyso adapted to the dimension c of the working head that the side of theworking head directed towards the neighbouring tooth is substantiallycompletely covered by means of the protection part 65. The protectionpart 65 is rigidly connected with the grip sleeve 1 and thus does nottake part in the oscillation movement. The protection part 65 may run asa protection strip from a pipe-like base part 66, that surrounds theshaft 41 at least partially with such a spacing that the shaft 41 andthe working head do not contact the base part 66 and the protection part65. In order to maintain the approximal dimension as small as possibleit is advantageous to arrange the protection part 65 in a recess of theworking head, at least partially sunk in. Such a configuration is shownin FIG. 15. This working head 42 e has a triangular or trapezoidalrecess 67 extending in its longitudinal direction, in which thereextends a correspondingly formed protection strip 65 at a small spacing(gap) from the recess surface.

As is already the case with the configurations in accordance with FIGS.1c, 2 a, 4 a and 6 a, with this configuration also the working region ofthe working head and the protection part 65 may be arranged inoppositely directed arrangement, namely rotated or turned byapproximately 180° or be arranged in another lateral arrangement, seeFIG. 1a. The protection part 65 likewise consists of corrosion resistantmaterial, in particular alloyed steel. The attachment to the grip sleeve1 may be effected by means of a releasible or non-releasible connection,e.g. by means of a screw connection or by means of a retaining nut.

As further protection devices, hindering the damage of neighbouringtooth surfaces, there may serve partial coatings or “inlays” on the toolsurfaces, the material properties of which such as e.g. the hardness orabrasivity do not damage tooth substance or repair materials, e.g.plastics such as teflon.

In the following, there will be described the treatment of a cariousdefect and/or a pre-existing repair of a tooth 21 in the approximalregion, with reference to FIGS. 16 to 22. The carious defect and/or apre-existing repair are removed by means of the preparation of thecavity K and moreover from the side of the occlusional region. Thispreparation may be effected with a working head 42 a which, in thepresent case of a lower jaw tooth, is sunk in—with oscillating tool3—from above. Thereby, the drive head 42 a may be supported with itsfree surface F on the neighbouring tooth 72, without there being thedanger of damage to the tooth 72, since only a slight frictional loadingoccurs. In place of the preparation with a working head 42 a inaccordance with the invention, a pre-preparation may be worked in with aconventional rotational tool 73 as shown by FIG. 16. As a precaution,when possible, this pre-preparation may be carried out except for a thinapproximal remainder wall 74, in order not to damage the tooth 72. Then,this pre-preparation is measured with regard to its width, length anddepth in order to be able to select the correct size for a subsequentrough and/or fine preparation with a drive head in accordance with theinvention of the correct size. Here, a measurement tool 75 isadvantageously suitable which will be described below. So far as thepre-preparation is effected without a remainder wall 74, theneighbouring tooth surface may be protected with a thin steel materialstrip and the relevant width of the pre-prepared cavity K up to thetooth 72 can be measured and a desired approximal safety spacing can betaken into account. The tool having the appropriate drive head 42 a isschematically indicated in FIG. 17. With regard to its dimensions b, cand d, the drive head 42 a is somewhat larger than the prepreparation sothat the prepared cavity K corresponds with regard to its form and size,taking into consideration the play S arising, to the form and size ofthe working head 42 a, so far as the drive head 42 a enters into thetooth 71.

FIGS. 19 and 20 show the drive head 42 a without divergent surfaces 59,which in the case of the present exemplary embodiment can be followed byworking with working heads 42 c, 42 d. The carrying out of the finepreparation with and without divergent surfaces is dependent upon thelater treatment technique.

The drive heads 42 to 42 e may have channel branches 27 a, 27 b, 27 cbranching off from the common supply channel 25, which channel branchesopen at the working surfaces and in oscillation operation cool theworking head and the tooth material, and wash away removed particles.

In FIG. 20, the grip sleeve 1 is furthermore formed with a schematicallyrepresented plug-in coupling 82, consisting of a plug-in hole 83 forinsertion of the shaft 41 and at least one coupling element 84 whichautomatically latches upon insertion into coupling recesses of the shaft41 and automatically un-latches upon pulling out. Further, the gripsleeve 1 has at its forward end an illuminating device 85 forilluminating the treatment site, preferably in the form of a lightconductor 86, extending longitudinally on or in the grip sleeve 1, thelight exit surface 87 of which is directed at the treatment site.

After, if appropriate repeated, measurement of the depth e of the cavitythere is effected the selection of one of a plurality of available,pre-fabricated inserts 91, prepared according to the respective bondingsystem being used with dental material, taking into account the lastused working head and if appropriate the depth e of the cavity K. Aftercleaning and if appropriate further conventional pre-treatment measures,and the application of a suitable bonding material 92 to the cavitywalls KW, the insert 91 can be set in the cavity in accordance withFIGS. 21 and 22 and bonded in conventional manner by means of thebonding material 92 with the tooth 71. For the purposes of improving theexit of excess bonding material, release grooves 90 may be arranged inthe contact surfaces of the insert 91, which release grooves preferablyextend to the occlusal region.

The pre-fabricated insert 91 may be of metal or composite plastics or atranslucent material such as e.g. glass, quartz or ceramics. Thedimension e1 of the insert extending longitudinally of the tooth axis,may be differently dimensioned for various reasons. If, after the fixedemplacement of the insert 91, an occlusal building up on the insert 91,if appropriate also for further regions of the tooth 71, is intendedthen the amount e1 may be less than the depth e of the cavity K.Otherwise the amount e1 should be somewhat greater than the depth e sothat the occlusal end region of the emplaced insert 91 can be adapted,with regard to dimensions and form, to a desired predetermined occlusalshape by removal of material before or after the fixing in place.

Since the insert 91 is matchingly pre-fabricated in the region enclosedby the cavity walls KW, an adaptation in this region is not needed. Theapproximal surface 91 a of the insert is likewise pre-fabricated wherebyits form and dimensions can be made ideal. With all configurations, thetool 42 and the insert 91 can have divergent surfaces 59 or bearingsurfaces 59 a, as is schematically illustrated in FIGS. 19 and 21.

With the exemplary embodiment according to FIGS. 21 and 22, an insert 91is employed which has at its occlusal end an application portion 93, ofa particular cross-sectional form and size, which projects beyond thedept e of the cavity K, and which application portion is preferablyformed integrally in the pre-fabrication. The application portion 93makes possible the manipulation and working of the insert 91 with aparticular handpiece 94 the forward region of which is illustrated inFIG. 22 in longitudinal section. This handpiece 94 has the form of athin rod which has at its forward end a functional arm 95 with a lateraladaptor part 96 for the application portion 93. With the presentconfiguration, the adaptor part 96 is formed by means of a matchingreceiving hole 97 for the adaption portion 93 and a clamping element 98for holding the adaption portion 93 or insert 91 at the adaptor part 96.The clamping element 98 may be formed by means of one or two oppositelylying lips or an annular lip 99 of elastic material such as plastics orrubber or hard rubber. The clamping effect is achieved in that theopening bounded by the lip or lips 99 is in cross-section smaller thanthe adaption portion 93 so that in the inserted condition a clampingeffect is present. Preferably, the functional arm 95 can be driven tooscillate by means of a drive in the handpiece 94 whereby the insert 91can by forcibly emplaced by means of the transfer of vibrations.

Further, a functional arm 95 may have at its free end region a lightgenerating device or a light conductor 101. With these means it ispossible with an insert 91 of translucent material to direct light tothe cavity walls KW from the light generation device or from the lightconductor 101 through the application portion 93—or if such is notpresent—directly from above into the translucent insert 91 and thus tothe cavity walls KW, in order to harden or cure a light or dual hardenor bonding medium 92, e.g. a fine hybrid composite.

After curing, the application portion 93 is worked away with the removalof material, taking into consideration the required matching form.

Within the scope of the invention it is further advantageous to haveavailable for each size or for the usual sizes a plurality of inserts 91of different coloring, in order to be able to select the insert 91 notonly with regard to its size but also its coloring and to adapt to giventooth colors.

Within the scope of the invention it is further possible andadvantageous to mold or press an insert 91A at the available workstation, whereby through mixing or selection of the molding or pressingmaterial an appropriate color can be provided for the insert 91A. Forthis purpose there is provided in accordance with FIGS. 23 and 24 acasting mold 103 with two mold parts 104 in which there are present inthe region of the dividing seam 105 at least one, preferably several,mold chambers 106 of shapes and sizes predetermined by the shapes andsizes of the available working heads. The mold parts 104 can be fastenedagainst one another through suitable means, e.g. by means of screws.Further, there is provided at least one container with a plastic moldingor pressing material for the molding/pressing of the insert 91A. Ifappropriate, a plurality of containers with molding/pressing materialsof different colorings may be available (e.g. light hardening fillingcomposite material's which after pressing into the negative mold in aclosed system/chamber can thereafter be tempered with light and/or heatand/or pressure) so that by means of the selection of the container aparticular color can be associated with the insert 91A. After selectionof the particular size of the insert 91A, taking into consideration thesize of the working head, the molding/pressing material is charged underpressure into the selected molding chamber 106 of corresponding size andshape which may be effected by means of an associated channel in thecasting mold 103. After curing of the thus formed insert 91A, adapted tothe size and shape of the working head used or to the cavity K, theinsert can be emplaced in the associated cavity and further worked.

With the above-described measures, an application portion 93 in thesense described above can also be formed when the associated moldchamber or mold chambers 106 also have an application portion 93 ofcorresponding form.

It is also possible within the scope of the invention to form theapplication portion 93 by means of a pre-fabricated core 107 whichconsists of the application portion 93 and an anchoring section 108 andis so arranged in the associated mold chamber 106 before the moldingthat the anchoring portion 108 projects into the mold chamber 106 andcan be formed around with the molding material. For receiving the core107 in the mold form 103 corresponding recesses are provided into whichthe core with its application portion 93 can be emplaced.

The measuring tool 75 has two measuring pins 111 which extend parallelto one another and have a length which is greater than the greatestdepth e of a cavity K. The cross-sectional size of the in particularround measuring pins 111 is preferably smaller than the smallestpossible cross-sectional size of a cavity K, so that large and smallcavities can be measured. The measuring pins 111 are each arranged on ameasuring arm 112 which arms are guided so as to be movable towards oneanother and away from one another in a guide 113. Thereby, the measuringpins 111 extend from the measuring arms 112, seen in the direction ofthe longitudinal axis 114 of the measuring tool 75, approximately atright angles to the guide plane E1. Seen transversely to thelongitudinal middle plane E2 of the measurement tool 75, the guide pins112 enclose with the guide plane E1 or the measuring arms 112 an angleW3 of approximately 70 to 135 degrees, preferably approximately 90 to110 degrees. In the present configuration, the guide 113 is formed bymeans of a joint 115 in which the two measuring arms 111 are connectedwith one another and which defines the guide plane E1 by means of theassociated joint plane. With the present configuration, the joint 115 isarranged at the ends of the measuring arms 112 away from the measuringpins 111. Between the measuring arms 111 there is arranged a spring 116,in particular a compression spring, which biases the measuring arms 112into their end positions, here into their spread-apart end position.Further, there is arranged between the measuring arms 111 a measuringdevice 117 having a scale 118, which makes possible a reading off of therespectively measured dimension of the cavitation. A second measuringdevice 119 is associated with one or with both measuring pins 111. Thismeasuring device 119 also has a scale 121 on the associated measuringpin 111, by means of which the depth e of the cavity K can be read off,as is illustrated in FIG. 18. It is also possible, preferably incombination with the scale 121, to arrange a clamping part, inparticular a clamping ring 122, on the associated measuring pin 111,which is displaceable and thus—with the measuring pin 111 set on thefloor of the cavity—is displaceable on to the occlusion surface of thetooth 71. In this way, either directly by means of comparison of thescale 121 with the occlusion surface or with the clamping ring 122, orby means of a measurement of the spacing of the clamping ring 122 fromthe free end of the measurement pin 111, the depth e can be determined.

In the case of a first treatment of carious defects lying inwardly inthe tooth, the opening of the tooth outer surface may be effected eitherdirectly with the oscillating instruments or after pre-preparation withrotating drills which are matched in terms of size, i.e. are smallerthan the oscillating instruments.

With the configuration according to FIG. 27 a tool 42 b in accordancewith FIGS. 4 to 5, of pear or lentil shape, is used to treat anapproximal primary carious defect. As is the case with theabove-described exemplary embodiments, the tool 42 b may be formed withor without neck surface 56 g. With longitudinal or transversely ovalextension of the caries to the approximal outer surface of the tooth 71a relatively small cavity K3 can be configured with the working head 42b, from the buccal, from the lingual or from the occlusal side, wherebyif appropriate pre-working with a smaller rotating tool may be effected.The working head 42 b can thus be sunk in and guided to the approximaltooth enamel defect. The lateral abrasivity is sufficient for theremoval of substance. Damage to the neighbouring tooth 72 is preventedby means of the free surface F. First, there arises an image of theworking head 42 b on the outer surface of the tooth 71. If thedecalcification zones of the caries extend further laterally, thedecalcification zone can be included in the preparation by means of ahorizontal sinking in of the working head 42 b or through a pivoting ofthe same in anti-clockwise direction (see the double arrows) whereby theschematically illustrated cavity K4 can be introduced. Thereafter, theworking head 42 b can be drawn back into the cavity K3 and then removedto the outside. By these means, the occlusal opening is reduced to aminimum. The treatment of the cavities can then be effected in a mannerknown per se.

With the configurations according to FIGS. 28 and 28a, in which the sameor similar parts or elements are likewise provided with the samereference signs, the repair of an in particular primary approximalcarious defect is effected through an occlusal or also lateral orlingual or buccal cavity K5, so that a destruction of the tooth enamelin the region of the approximal tooth surface which has not beenaffected by the caries is avoided so far as possible. This measure issuitable in particular when the tooth 71 to be treated has alreadyreceived an occlusal, lingual or buccal preparation, so that a cavity K5already present or, if applicable to be made free, can be exploited forthis cavity K6.

With this configuration, the tool 3 is formed with an angle-shape or aZ-shape, whereby the working head is formed by means of the free endlimb of the angle or Z-shape. The cross-sectional form of the workinghead 42 may be circular or oval in vertical or horizontal direction. Theangle w5 enclosed between the shaft 41 and the working head 42 ispreferably a slightly obtuse angle and may be between approximately 90°and approximately 110°. The cross-sectional dimension g of the workinghead 42 may be approximately 0.8 to 2 mm. For small cavities K6, thecross-sectional dimension g is approximately 0.8 to 1.2 mm. Relative tothis, the cross-sectional dimension g1 of the shaft 41, in particularround in cross-section, should be approximately the same or somewhatsmaller. The length h of the working head 42 may be approximately 1 to 3mm, preferably 1.5 to 2 mm. The length h1 of the shaft section 41 a—inthe case of a Z-shape tool 33 the middle shaft section—should be solarge that approximal defects can also be reached even in deeper regionsof the tooth, so that one and the same tool 3 can be put to use forcarious defects lying at different depths. Preferably, the length h1 isapproximately 5 to 10 mm. The preferably obtuse angle between the shaftsections 41 a and 41 b may correspond to the configurations according toFIGS. 1 to 4 a and is preferably approximately 90 to 120°. Thecross-sectional size of the working head 42 may be slightly convergenttowards its free end, in order to make more easy the withdrawal inwardlyout of the cavity K6. Since, however, the cross-sectional size of thecavity K6 may preferably be made larger, the above-mentioned convergentshape of the working head 2 is not an absolute necessity. The workinghead is abrasive at its peripheral surface and its end surface.

The cross-sectional depth and size of the cavity K5 should be so largeat the tool 3 can be readily introduced with the working head 42.

FIG. 28a shows the treated defect, whereby the cavities KS and K6 areable to be filled and thus treated with the same material or withdifferent materials. For filling, materials which are applied in aplastic form, of medium viscosity, are suitable, e.g. composites andcomposite thermoplastics (Kompionomere). It is possible to work on thelarger cavity K5 with a working head 42 which, in cross-section, hascorners or is round, in accordance with FIGS. 1 to 1 b, e.g. after aprior opening by means of a conventional rotating drill. It is also ofadvantage to provide the cavity K5 with an insert 91 the cross-sectionalform and size of which are adapted, in the sense in accordance with theinvention, to the cross-sectional form and size of the working head 42(see e.g. FIGS. 1a and 1 b).

Above-described tools can also be employed very advantageously for theremoval of a furcation problem which arises in the case of paradontalbone atrophy at teeth with on or more roots and includes in the case ofpartially or completely opened furcations, contaminations, incidence oftartar and sources of bacterial infections. Such a furcation problem canbe removed very well the tools 3 in accordance with the inventionwhereby in such cases in which the neighbouring surfaces should remainuntreated, tools 3 having a free surface F can be employed, such as isthe case e.g. in the approximal furcation region or in the furcationregion of teeth with multiple roots.

FIGS. 29 to 36 show tool configurations which are advantageouslysuitable for the removal of furcation problems.

With the configuration according to FIGS. 29 to 31, the tool 3 consistsof a connection part for connection with a schematically representedholder and drive part 128 of a handpiece, whereby the drive part 128 isoscillatingly driven in the longitudinal direction of the tool 3. Here,short oscillations may be involved which are generated by an oscillationsource 2 or also longer to and fro movements may be involved such as isper se the case with handpieces for file tools for root canal treatmentor the like.

With the present configuration, the connection part is formed by meansof a sleeve-like clamping clasp in the form of a small tube 129longitudinally slit by means of a slit 130, which can be plugged onto,and held thereon by means of clamping tension, a drive part ofcorresponding cross-sectional form, preferably cylindrical. From theclamping clasp 131 there extends a flat shaft 132 either straight orlaterally offset forwardly, on the free end of which a working head 133is arranged. The shaft 132 is elastically bendable laterally.Preferably, the tool 3 is formed as a stamped bending part from aone-piece blank, whereby the clamping clasp 134 is bent and the workinghead 133 is deep drawn, referably towards the side towards which theclamping clasp arms of the clamping clasp 131 are bent. The tool ispreferably of a hard metal, in particular alloyed steel.

The convex outer surface 134 of the working head 133 is provided, in thesense already described, with a plurality of in particular point-likecutting edges which are arranged distributed and preferably consist ofhard adherent grains, preferably of diamond, feldspar or ceramics, sothat the working head 133 is abrasive at its working surface 134 andensures a removal of material.

The head surface 134 a and the side surfaces 134 b of the convex workinghead 133 may be correspondingly abrasively formed. Also, the forward andrearward end faces 134 c may be correspondingly abrasively formed. Thehead surface 134 a is rounded at the transition into the other remainingworking surface sections. The cross-sectional form of the working head133 may thereby be flatly rounded or hemispherically rounded. The lengthi of the tool 3 projecting from the connection part may be approximately10 to 30 mm, in particular approximately 15 to 20 mm.

With the configuration according to FIGS. 32 and 33, the working head133 has—preferably in its rearward end region—a transversely extendingworking edge 135 which may extend only in the region of the head surface134 a or also in the region of the side surfaces 134 b and which may bestepped edge, which is of the material of the working head 42 or may beformed by means of a coating of the above-mentioned abrasive materials.

The length k of the working head 42, diamondised on its workingsurfaces, may be approximately 1.5 to 5 mm, preferably about 2.5 mm.This applies also for the width m, which in the present exemplaryembodiment is about 2 mm. With the present flat configuration of theworking head 42, the thickness n is about 0.5 to 2 mm, preferably about0.75 mm. Insofar as the working head 133 is offset to the siderelatively to the shaft 132, this amount of offset o may beapproximately 0.5 to 3 mm, in particular approximately 0.75 to 1 mm.

With the configuration according to FIGS. 35 and 36, for which the sameor similar parts are designated with the same references signs, thedrive head 133 has at its lateral working surface at least onetransversely extending waist 112, the waist surface 136 a of which isrounded. The radius r of this rounding is preferably somewhat largerthan the radius of the tooth shape to be worked on. By these means, theabrasive treatment of a tooth surface, in particular in the root regionof a furcation, is substantially simplified because the tooth surfaceparts before and behind roundings present can be better reached and thetool 3 need be moved less in order to reach these surface regions. Ascan be understood from FIG. 35, with a direction of view onto theworking surface 134, the head end of the working head 133 is rounded,preferably hemispherically rounded, whereby this rounding transformsinto the waist 136. Further, at an axial spacing from the waist, thereis in the starting region of the working head 133 a “half” waist 136 awhich forms a cross-sectional tapering directed toward the shaft 132.This working head 133 can, in cross-section, be formed flat inaccordance with FIGS. 32 to 34 or rounded, in particular half-roundedwith flat reverse side or completely rounded, in particular circularlyrounded. Thereby, the reverse side, visible in FIG. 36, may be anon-abrasive smooth free surface F or may be formed to be abrasive inthe above-described sense as with the other head and side surfaces, 134a, 134 b. As FIG. 36 likewise shows, with the present configuration thereverse surface 137 opposite to the head longitudinal surface 134 a iswave-like with a snake shape or S-shape, whereby two further one-sidedwaists 136 b, 136 c are formed which are axially offset relative to thewaist 136, so that the waist 136 lies opposite, at the reverse surface137, a rounded protrusion. The rounding surfaces 138 of these waists 136b, 136 c and the rounded protrusion therebetween may have the same orpreferably a somewhat larger radius r1 than the radius r of the waists136, 136 a, whereby—with an abrasive reverse surface 137—throughselective use of the head longitudinal surface 134 a or the reversesurface 137 an adaptation to tooth cross-sections of different sizes ispossible.

The abrasive working surfaces of this working head 133 are preferablydiamondised. The diamondisation is 40, 15, 2 to 4 μm.

The configuration of a working head 42 of the tool 3 shown in FIGS. 37to 39 is a further development of the configuration according to FIGS.2, 2 a and 3, whereby the same or similar parts are provided with thesame reference signs. This configuration differs from theabove-described in the following details:

First it is to be explained that this working head 42 is, for thepurpose of simpler representation, shown in a position in which it—incomparison with its real position in the mouth—is slightly tilted in theanti-clockwise direction, which is made more clear by means of themiddle line indicated by V which is intended to represent the vertical,which extends parallel to the theoretical vertical middle axis of thetooth 71 to be treated. In the real position, the free surface F islocated in an approximately vertical position, depending upon how thedentist positions the working head 42.

A first difference consist in that the working head 42—as seen in a viewfrom above or the view from below according to FIG. 39—is curved inapproximate adaptation to the peripheral form of the tooth 71, whereby aconcavely curved front surface 56 b is provided. This transforms withrounding into the side surfaces 56 c which are adjoined by the divergentsurfaces 59 at all three sides present (lateral and lower). Thedivergent surface section 56 a, starting from the floor surface 56 d,develops correspondingly curved, whereby this edge surface section ofthe cavity K is likewise approximately adapted to the curvature of atooth outer surface. The reverse surface 56 a is likewisecorrespondingly curved in principle. With the present configuration, thereverse surface 56 a has a flat reverse surface part 56 a 1 whichextends in the middle region of the working head 42 (see FIG. 38) overthe whole height of the working head, but in the lateral regions—becauseof the curvature of the reverse surface 56 a —extends only over partregions, as can be understood from FIG. 39. Through the concavecurvature of the front or working surface 56 b lesser tooth material istaken away from a tooth 71 to be prepared, which contributes to thestability of the tooth.

A further difference consist in that at least at the lower side of theworking head 42—in the case of the present configuration also the sidesurfaces—there projects a narrow step 125 slightly downwardly orlaterally, here by an amount p of approximately 0.2 to 05 mm, at whichthe divergent surfaces 59 end. The thickness g of the step 125 isapproximately 0.1 to 0.4 mm preferably about 0.2 mm.

The working head 42 is suitably for working in (if appropriate afterprevious preliminary work with a rotating drilling tool) both for acavity K for an inlay or insert 91 (see e.g. FIG. 21) and also forworking in or final working (possibly after preliminary work with arotating drilling tool) of a cavity K for a tooth crown according toFIG. 40. In the case of provision of a tooth crown it is advantageous towork in the cavity so far that the step 125 forms a gingival step 126.In the case of the preparation of a cavity K for an inlay or insert 91this can be carried out with or without gingival step 126.

The width s of the drive head 42 or of the cavity K is to be determinedin accordance with the corresponding width of the carious defect. Thegreater the width s is i.e. the greater is the region of the curvature,the greater is also the angle w6 enclosed by the lateral divergentsurfaces 59. With wide working heads 42 or cavities K. the angle w6 maybe (depending on the size of the angle w1 ) 90° and more, e.g. in theregion of premolars. It is thus advantageous to provide or to store aplurality of working heads 42 of different width s in order to haveavailable a suitable working head for normal treatments. This appliesalso to correspondingly associated inlays or inserts 91 with regard totheir width and their lengths e1 to be determined or likewise providedin steps, which also applies for all other above-describedconfigurations of the working heads 42.

The divergence of the working head 42, directed towards the free endthereof, of approximately 2 to 8°, in particular 4 to 6°, is madeclearer in the case of the configuration according to FIGS. 37 to 39 bythe angle w7 . Also with this configuration there may be provided in theworking head 42 a cooling channel 27 opening out at the front surface 56b or a plurality of cooling channel branches opening out at the workingsurface part.

What is claimed is:
 1. A tooth filling system for preparing and fillinga cavity which extends into the side of a tooth, said system comprising:a vibratable tool having abrasive front and side surfaces, said sidesurfaces extending back from said front surface at an angle ofdivergence, whereby, upon vibration of said tool against the side of atooth, said tool forms a cavity having cross-sections of the same sizeand shape as corresponding cross-sections of said tool; and an insertcomprising a solid body formed with a tooth adhering region defined by alateral front surface and lateral side surfaces which extend back fromsaid front surface to a free surface of said insert, said insert havingcross-sections which correspond in size and shape to the size and shapeof corresponding cross-sections of said tool.
 2. A tooth filling systemaccording to claim 1 wherein: the side surfaces of the insert arebearing surfaces for abutting cavity walls formed by said tool and whichare convergent in a direction in which said front surface faces.
 3. Atooth filling system according to claim 1 wherein: the side surfaces ofthe insert are flat surfaces which extend in a straight manner in a thedirection in which said front surface faces.
 4. An insert according toclaim 1 wherein: said insert is one of several inserts which differ fromone another in at least one of the dimensions of their cross-sectionalshape, their and their dimension extending at a right angle thereto. 5.A tooth filling system according to claim 1 wherein: the insert is madeof a material chosen from the group consisting of metal, plastic,composite plastic, light transparent material and glass ceramics.
 6. Atooth filling system according to claim 1 wherein: said insert is aninsert chosen from the group which consists of approximal, occlusal,incisal, buccal and lingual inserts and wherein a free side surface ofsaid insert is pre-fabricated.
 7. A tooth filling system according toclaim 1 wherein: the insert includes an application portion in anocclusal portion portion thereof.
 8. A tooth filling system according toclaim 1 wherein: said insert is one of several inserts which havediffering widths, and wherein the angle enclosed by the divergingsurfaces of each insert is larger the larger the width of the insert. 9.A tooth filling system according to claim 1 wherein said abrasive sidesurfaces of said tool converge in their working direction.
 10. A toothfilling system according to claim 1 wherein said lateral side surfacesof said insert are convergent in a direction toward said lateral frontsurface.
 11. A method of repairing a tooth comprising the steps of:forming a cavity in a tooth by causing a tool to be vibrated against aside of said tooth, said tool comprising a solid body and havingabrasive front and side surfaces, said side surfaces extending back fromsaid front surface at an angle of divergence, the cavity formed by saidtool being characterized by an inner surface within said toothcorresponding to the front surface of said tool and side surfaces whichextend from said front surface at an angle of divergence out to an outersurface of said tooth; and thereafter placing into said cavity apreformed insert which has external dimensions corresponding to theinternal dimensions of said cavity.
 12. A method according to claim 11wherein the step of forming a cavity comprises moving said tool in aworking direction into said tooth to form tooth cavity walls which areconvergent in the direction of working.
 13. A method according to claim11 wherein the step of forming a cavity includes the step of formingcavity walls with flat surfaces of said tool.
 14. A method according toclaim 11 including the step of providing an insert which is made of amaterial chosen from the group consisting of metal, plastic, compositeplastic, light transparent material and glass ceramics.
 15. A methodaccording to claim 11 including the step of providing an insert from thegroup which consists of approximal, occlusal, incisal, buccal andlingual inserts and wherein the chosen insert is pre-fabricated.
 16. Amethod according to claim 11 including the step of providing an insertcomprises which has an application portion in an occlusal portionportion thereof, which application portion projects beyond the depthextent of a cavity into which the insert fits.
 17. In combination, atleast one vibratory abrasive tool for preparing cavities in teeth; and agroup of inserts for filling said cavities, said inserts each comprisinga solid prefabricated body which has a front surface and side surfacesextending back from said front surface, at least the rear portion ofsaid side surfaces extending at an angle of divergence, said insertsbeing of similar configuration and having front surfaces of differentwidths and side surfaces whose angle of divergence is increased withincrease width of their respective front surfaces.